1. Field of the Invention
The invention relates to a blood purifying device for purifying the patient's blood by means of extracorporeal circulation or an infusion device for administering drugs into the patient's body.
2. Description of Related Art
In a conventional dialysis treatment, a puncture needle attached to the distal end of the blood circuit is caused to puncture into the patient's body, while the patient's blood is caused to make an extracorporeal circulation in order to purify the blood by means of a dialyzer connected to the circuit. Such a dialyzer is connected to a dialysis device, wherein said dialysis device provides a dialysate and discharges the dialysate containing waste products of the blood.
In other words, a blood passage (the ends of which are connected to the arterial side blood circuit and the venous side blood circuit respectively), through which the patient's blood flows, and a dialysate passage (the ends of which are connected to the dialysate induction line and the dialysate discharge line respectively), through which the dialysate flows, are formed in the dialyzer, and these passages are separated by a hollow thread membrane, so that it is possible to diffuse the products contained in the blood flowing through the blood passage across the membrane into the dialysate, thus purifying the blood, and return the purified blood back to the patient's body.
The dialysis device is provided, primarily inside the device, with an operating input unit for the operator, such as a medical doctor, to start or stop the dialysis treatment, or to set up or change the dialysis treatment condition, as well as a operation unit that executes prescribed operations (including the start and stop of the device and controls based on various setups) based on input signals entered through said input unit. The operation input unit contains touch operating type switches displayed on the liquid crystal display panel, operating switches and operating dials that can be operated for entering input data mechanically, etc.
There is a possibility, for example, that the terminal point of an operating switch can be held in a contacting state temporarily or continuously due to a malfunction of said operation input unit or an external noise, while the operator is not operating. Such a problem must be avoided as it can threaten the patient's life in a medical device such as a dialysis device.
In order to avoid the operation unit from functioning due to a temporary contact of the terminal point of an operating switch although the operator is not operating, a medical device has been proposed wherein a switch is not recognized to be pressed unless said switch is continued to be pressed for a prescribed period of time (hereinafter called “maintained operation”). Also, another medical device has been proposed wherein a timer is provided for detecting the same operating condition is held continuously over a prescribed period of time and determines that a malfunction has occurred when said timer detects such an incidence in order to avoid the operation unit from operating when the same operating condition continues over a prescribed (long) period of time although the operator is not operating. Those medical devices improve the safety during treatments as they prevent the operation unit from causing unintended operations due to malfunctions or external noises. These prior arts are not related to any publicized inventions, so that there is no prior art documents to be referred here.
Problems to be Solved by the Invention
However, those medical devices of the prior art needing maintained operations accept operating input only when a switch is pressed continuously for a prescribed time, it presented a problem that it is difficult to achieve the ease of operation and safety of the device simultaneously. In other words, it tends to cause misrecognition of an error signal as a normal signal if the prescription time for a maintained operation is set too short, while it may reduce the ease of operation as it requires to be pressed too long if said prescription time is set too long.
Moreover, in case of a medical device of the prior art equipped with a timer, it may deteriorate the ease of operation as it tends to cause normal operation input by the operator as a malfunction if the set time for recognizing malfunctions is chosen too short, while safety may be jeopardized in the operation of the operation unit as it takes too long to recognize malfunctions if the set time is chosen too long, thus making it extremely difficult to properly set the time for avoiding malfunctions.
The invention was made under such a circumstance, and provides a medical device which makes it possible to achieve both the ease of operation at the operation input unit and the patient's safety at the same time.